Edge temperature gradient as intrinsic rotation drive in Alcator C-Mod tokamak plasmas

Intrinsic rotation has been observed in I-mode plasmas from the C-Mod tokamak, and is found to be similar to that in H mode, both in its edge origin and in the scaling with global pressure. Since both plasmas have similar edge ?T, but completely different edge ?n, it may be concluded that the drive of the intrinsic rotation is the edge ?T rather than ?P. Evidence suggests that the connection between gradients and rotation is the residual stress, and a scaling for the rotation from conversion of free energy to macroscopic flow is calculated.